It is the first time since the assassination of Martin Luther King in 1968 that the National Guard had to be deployed in Baltimore.
Thousands of police officers and National Guards are trying to prevent civil unrest, which observers note has been in the making for several years.
The death of Freddie Gray, who died last week after suffering a severe spinal cord injury in police custody, has sparked a series of violent protests that now threaten to disturb the peace of the entire country.
Here we have complied a guide to the events that brought thousands in Baltimore out on the streets:
Who is Freddie Gray?
Freddie Gray was a 25-year-old African American, who was taken into custody by the Baltimore Police Department on 12 April. But while being taken to the police station, Gray fell into coma after suffering injuries to his spinal cord and larynx. He died on 19 April. Gray lived with his sisters in the Gilmor Homes neighbourhood. He had a criminal record, mainly for misdemeanour and drug-related offences.
Why was Freddie Gray arrested?
The Baltimore Police Department arrested Gray for the possession of a switchblade. According to a Baltimore Sun investigation, Gray and another man "briefly locked eye" with the police officers, before fleeing the scene as they approached him. The police officers started a chase and tackled Gray and then put him in a police van to take him to the station.
How did Freddie Gray get injured?
There is still no clarity on this. The police officers have claimed they never used force while arresting Gray. However, a video and eyewitness accounts claim that he was pinned down and dragged to a police van. One eyewitness claimed that he saw Gray "screaming for his life" after an officer's thrust his knee on the 25-year-old's neck.
Did Gray sustain spine injury a week before the police arrest?
A report has now emerged that Gray received the spinal injury as the result of a car accident. The Fourth Estate reported that he was recovering from a spinal and neck surgery he allegedly received a week before. For the surgery, he also received a large structured settlement from Allstate Insurance.
Freddie Gray failed to get immediate medical attention
According to Police Commissioner Anthony Batts, "officers should have provided medical attention immediately following the arrest of Freddie Gray." Instead, they handcuffed Gray and put him in the back of a van without even buckling him.
The van then made three different stops across town. Gray who had asthma, even after his repeated requests, was not provided any medical assistance by the officers. It was only after an hour when his condition worsened that the paramedics were called.
What action has been taken against the police?
Since Gray's arrest, six officers have been suspended with pay and placed on desk duty. At least three officers involved in the Freddie Gray case are white as seen in the video clip take by eye witnesses.
What does the Freddie Gray arrest video tell us?
An eyewitness captured the Freddie Gray arrest on his cellphone. The footage shows a limp Gray being dragged by the police officers, while bystander are heard screaming, "That boy's leg looks broke!"
How has Freddie Gray's family reacted to the tragedy?
Gray's mother, Gloria Darden, told NBC that she wants justice for her son but urged protesters not to "do it like this." "Don't tear up the whole city just for him," she said. "That's wrong."
His stepfather condemned the rioting, which broke out in Baltimore, saying he was "appalled" that protests over Gray's death had descended into chaos. "To see that it turned into all this violence and destruction, I am really appalled," Gray's stepfather Richard Shipley said.
Baltimore Riots was decades in the making
The Baltimore riots was long in the making, even before the mysterious death of Freddie Gray.
According to a report in Slate, the high rate of job attrition and lack of decent wage has made Baltimore vulnerable to drug trade. The city also has seen a high number of police brutality, especially in the area where Freddie Gray grew up.
The words of a Freddie Gray protester Pierre Thomas sums up the frustration among the people in the area. He told NPR that everyone starts talking about "peace" only when the powerful feel threatened.
"Where was the peace when we were getting shot? Where is the peace when we are in the back of ambulances? Where is the peace then?" Thomas said.
"They don't want to call for peace then. But you know when people really want peace? When the white people have to get out of bed, when cops have to wear riot gear, when the cops start talking about, oh we got broken arms. Then they want peace."
"Peace? It's too late for peace," he concluded.